Thermal Management Of A Personal Computing Apparatus

ABSTRACT

A method and system are provided for thermal management of a portable computing apparatus. Accelerometers are provided to detect changes in attitude, and temperature sensors are provided to detect changes in temperature. A fan is used to cool the internal temperature of the electronic components of the computer. In response to lift of the computer from a stationary surface, the computer may transition to an alternative state of operation. The transition may include the change of the speed of the fan and/or adjustment of the processor clock.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application is a continuation of application Ser. No. 11/032,726,filed on Jan. 11, 2005, now pending, which is hereby incorporated hereinby reference.

BACKGROUND OF THE INVENTION

1. Technical Field

This invention relates to thermal management of a personal computer.More specifically, the thermal management applies to detection ofmovement of a personal computer from a stationary surface and managingcooling of heat generating components in response to the movement.

2. Description Of The Prior Art

It is known in the art that electronic parts in computer systemsgenerate heat. Fans and heat sinks have been developed to manage heatdissipation of electronic parts. Laptop computers are a category ofpersonal computers that are relatively compact and, as such, areportable. However, problems arise when a user of a laptop computer movesthe laptop from a stationary position on a stationary surface, to theirlap or another part of their body. The problems that arise are found inexcess heat reaching the surface of the body of the user through a basesurface of the computer, which can cause discomfort. Accordingly, thereis a need to accurately detect movement from a stationary surface and toefficiently dissipate heat from the computer components so that a userof the laptop will not suffer discomfort.

There are several patents that address thermal management of a laptopcomputer. For example, U.S. Pat. No. 6,760,649 to Cohen provides apressure sensor on a base cover of a laptop computer to determinewhether the base surface of the laptop is in direct contact with a lapof the user and to initiate a cooling function in response to activationof the pressure sensor. When the laptop is on a stationary surface, thepressure sensor does not become activated since the sensor hasconsideration for a gap frequently formed between the base surface of alaptop casing and a resting surface, such as a stationary surface. Assuch, the pressure sensor does not activate on a stationary surface.However, there are limitations associated with the '649 patent to Cohen.For example, an erroneous determination may arise when the user of thelaptop is not in direct contact with the base surface of the casing. Onesuch example is if an object becomes caught between the casing andstationary surface, or an edge of the stationary surface is detected asa lap when a portion of the casing is placed into a position to jut outfrom the stationary surface without support. Activation of the sensorresults in initiation of cooling measures, which in turn results in anincrease in fan noise and may result in lowering the frequency of theprocessor clock. Cooling measures which lower the frequency of theprocessor clock affect the performance of the personal computer. If thecooling measures are initiated in response to a false reading of asensor, then the personal computer may inappropriately operate at alower performance level. Accordingly, the prior art does not address theneed for an accurate tool for detecting movement of a laptop from astationary surface.

Therefore, there is a need for an accurate method of determining when alaptop computer has been moved from a stationary surface to a lap of auser or other part of the body. The method should include the entiresurface area of the base surface of the laptop, and restrictivelyrespond to the movement with a minimal thermal management adjustment sothat the adjustment should not interfere with internal or externaloperations of the computer.

SUMMARY OF THE INVENTION

This invention comprises a method, system, and article for thermallymanaging a personal computer subject to movement from a stationaryposition.

In one aspect, a method is provided for cooling a portable computingapparatus. Movement of the computer from a stationary surface isdetected. The detected movement includes a change in inclination of thecomputer casing. It is then determined if a target temperature has beenexceeded in response to the detected movement. If it is determined thatthe target temperature has been exceeded, the computer transitions to analternative cooling state.

In another aspect of the invention, a portable computing apparatus isprovided. The portable computing apparatus includes a detector to sensetilt movement of the computer from a surface. A sensor is also providedto determine if a target temperature has been exceeded in response tothe detected movement. If the determination is positive, a controllertransitions the computer to an alternative cooling state.

In yet another aspect of the invention, an article is provides withmeans to detect a lift movement of a computer from a stationary surface.Means are also provided to determine if a target temperature has beenexceeded in response to the detected movement, and to transition thecomputer to an alternative cooling state in response to a positivedetermination.

Other features and advantages of this invention will become apparentfrom the following detailed description of the presently preferredembodiment of the invention, taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of internal sensors and thermal managementcomponents of the computer according to the preferred embodiment of thisinvention, and is suggested for printing on the first page of the issuedpatent.

FIGS. 2 a and 2 b are flow charts illustrating a process for determininga change in attitude of the computer.

FIG. 3 is a flow chart illustrating a process of changing an operationmode of the computer in response to a lift movement.

FIG. 4 is a flow chart illustrating a process of entering a rapidcooling mode for a period of time in response to entry into a laptop usestate.

FIG. 5 is a flow chart illustrating a process of maintaining a rapidcooling mode before reduction to a target temperature.

DESCRIPTION OF THE PREFERRED EMBODIMENT Overview

One or more temperature sensors are provided to detect an internaloperating temperature of a computer, and one or more accelerometers areprovided to determine a change in attitude of the computer. In addition,one or more fans are placed inside the casing of the computer to managethermal output of electronic components therein. The temperature sensorsand accelerometers function together with associated logic to balanceperformance of the computer while mitigating the casing surfacetemperature of the computer. At such time as a change in attitude of thecomputer is detected, an operational mode of the computer may beadjusted to quickly cool the casing surface temperature so that a userof the laptop would not be discomforted by a high surface casingtemperature.

Technical Details

FIG. 1 is a block diagram (10) of internal components of a portablecomputing apparatus, such as a laptop, and the elements therein thatcontrol operation and performance of the computer. As shown, there is anacceleration section (12) which includes accelerometers to detectacceleration of the personal computer in relation to detecting a changein inclination, and a casing surface temperature detection section (14),which includes one or more temperature sensor(s) to detect the surfaceof the casing. The acceleration section (12) is in communication with ause style determination section (16), which is in communication with anattitude variation recording section (18). The use style determinationsection ascertains the preferred mode of use of the computer in responseto data received by the acceleration section (12) and data stored in theattitude variation recording section (18). The attitude variationrecording section (18) stores data variations received from theaccelerometer at predetermined time intervals and compares them to arecord of variations in an earlier time period. Based upon comparisonsof acceleration data, a style of use of the laptop may be ascertained.The result of this determination is one of style of use in which a useris probable to have direct contact with the casing surface and a stylein which a user is not likely to have direct contact with the casingsurface. The determination results are communicated to a cooling controlsection (20) which provides thermal management to the laptop computer.The time intervals at which determination results are sent from thedetermination section to the cooling control section are preferably setto coincide with the intervals at which acceleration and inclinationdata are sent from associated accelerometers to the use styledetermination section (16). In one embodiment, the frequency in whichthe determination results are forwarded to the cooling section may beadjusted. In addition, obtained surface temperature values are suppliedfrom a casing surface at predefined time intervals. Based on acombination of the surface temperature and the determination resultsfrom the user style determination section (16), the cooling controlsection issues a cooling request to a clock control section (22) and/ora fan control section (24) as required each time the casing surfacetemperature reaches an upper style limit. In one embodiment, one of thecontrol sections, i.e. clock and fan, to which the adjustment requestwill be sent is selected with priority of adjustment. Accordingly,accelerometers and temperature sensor data are obtained to determine anoptimal thermal management mode.

In one embodiment, the use style determination section and the attitudevariation section communicate with a device driver in response to adetermination that there has been an attitude adjustment. The comparisonof attitude data contributes to providing an accurate determination ofchanges in attitude of the laptop computer. If the attitude variationrecording section (18) provides data of a significant change inattitude, the device driver transmits a communication to the coolingcontrol section (20). In one embodiment, the cooling control section(20) communicates with the BIOS which supports control of the processorclock and fan speed. The clock control section supports a change in theclock of the processor, i.e. a greater clock speed results in a greaterthermal output. Similarly, the fan control section provides support foradjustment of the speed of the fans, which may need to be increased toprovide greater cooling capacity. Accordingly, data gathered from theaccelerometer(s) together with the temperature sensor(s) are used tocommunicate external data to a device driver in communication with BIOSthrough a program manager utility to provide adjustments to the fanand/or processor to enhance cooling.

As shown in FIG. 1, the casing of the laptop computer includes one ormore accelerometers to detect a change in attitude of the computer. FIG.2 a is a flow chart (50) illustrating a process for processing andmanaging data received from the accelerometers. Inclination data isobtained on the present attitude of the casing (52), and the data inassociation with the time period in which it was obtained is saved as arecord (54). Thereafter, a test is conducted to determine if the laptopcomputer was stationary during the time period in which the inclinationdata was obtained (56). In one embodiment, inclination data may beobtained in 20 second intervals, although such time intervals may beadjusted to be increased or decreased. If the response to the test atstep (56) is negative, this is an indication that the accelerometershave determined that there has not been a change in attitude (58).However, if the response to the test at step (56) is positive, asubsequent test is conducted to determine if the laptop computer hasbeen stationary for a long time period (60). The term stationary maysupport a change in inclination data that is within a defined margin oferror. A positive response to the test at step (60) will result inanother test to determine if the data obtained in the most recent timeperiod is identical to data in a prior inclination data record (62). Ifthe response to the test at step (62) is negative, the presentinclination data record is registered as a stable horizontal position(64) and a test is conducted to determine there are any registeredhorizontal positions that have not been accessed for a long period oftime (66). A positive response to the test at step (66) will supportremoval of the registered and unused horizontal position data (68).Accordingly, the first part of the lift determination involvesdetermining if the computer has been in a stationary position for anextended period of time.

FIG. 2 b is a flow chart illustrating the remaining steps of determininga lift of the computer from a stationary position. Following a negativeresponse to the test at step (66), a positive response to the tests atsteps (60) or (62), or following step (68), the next registered stablehorizontal position data record is read (72) to further determine ifthere has been a lift of the laptop from a stationary position.Following the read at step (72), a test (74) is conducted to determineif the current inclination data obtained at step (52) is equal to theregistered stable position data read at step (72). A positive responseto the test at step (74) results in a determination that operation ofthe laptop computer is being performed in a stable condition and thestyle of use has been identified (76). Alternatively, a negativeresponse to the test at step (74) will result in a subsequent test (78)to determine if there are any additional registered horizontal positiondata records that have not been compared to the inclination dataobtained at step (52). A positive response to the test at step (78)results in a return to step (72). However, a negative response to thetest at step (78) results in a determination that there is a possibilitythat the laptop computer has been lifted and that the thermal managementmode of operation should be adjusted (80). If the time period duringwhich variations in the inclination of the casing are monitored isexcessively short, there is a possibility of an unstable attitude beingerroneously detected as a stabilized attitude when the extent ofvariation becomes small. Occurrence of such an erroneous detectionresult may be prevented by adding a time period during which the measureto achieve a reduction in noise or an improvement in performance cannotbe taken. Accordingly, the process of managing accelerometer datasupports processing the data and comparing the data to prior readings inorder to determine if there has been a significant change in attitude.

The purpose of detecting attitude and temperature data is to accuratelydetermine when there has been a lift of the laptop from a stationaryposition and to respond accordingly to prevent excess heat from beingtransmitted to a user from a casing surface of the computer. FIG. 3 is aflow chart (100) illustrating one embodiment for employing the thermalmanagement of the laptop computer in response to a lift of the computer.Following a lift of the laptop, the device driver associated withattitude adjustments notifies the power manager utility that the laptophas been lifted (102), followed by the power manager utility notifyingthe BIOS of the movement (104). In one embodiment, the lift isdetermined in response to the processing of inclination data shown inFIG. 2. The BIOS reads the temperature of the processor, video card, andother heat producing electronic items in the laptop (106). Thereafter, atest is conducted to determine whether or not a target internaltemperature in the laptop has been exceeded (108). The target internaltemperature is a designated temperature set as a limit which if exceededwill require the thermal management system to enter into a coolingphase. If the test at step (108) indicates the target temperature hasbeen exceeded, the BIOS sends instructions to adjust the processor clockspeed and fan speed to make a transition to a forced cooling mode (110).Entry into the forced cooling mode changes the speed of an internalcooling fan and forcibly reduces the clock speed of the CPU and video.However, if the test at step (112) indicates the target temperature hasnot been exceeded, the BIOS issues instructions for immediate transitionto a laptop use state (112). Entry into the laptop use mode requiresadjustment of the speed of the cooling fan, the speed of the CPU andvideo to balance performance, thermal output, and noise level. Followingstep (112), the device driver notifies the power manager utility thatthe system has entered a laptop use state (114), and the power managerutility notifies the BIOS of the transition to laptop use state (116).Thereafter, the BIOS changes the cooling fan speed, as well as CPU andvideo performance settings (118). Accordingly, the process illustratedin this embodiment demonstrates a method for initiating entry into aforced cooling mode or a laptop use mode in response to a lift of thelaptop from a stationary position.

FIG. 4 is a flow chart (150) illustrating an embodiment for employingthe rapid cooling mode for a defined period of time. Following thedevice driver notifying the power manager utility that the system hasentered a laptop use mode (152), the power manager utility notifies theBIOS of the entry into the laptop use mode (154). The BIOS reads thetemperatures of the CPU and video with use of temperature sensors (156).Thereafter, a test is conducted to determine whether or not a targetinternal temperature in the laptop has been exceeded (158). The targetinternal temperature is a designated temperature set as a limit which ifexceeded will require the thermal management system to enter into acooling phase. If the test at step (158) indicates the targettemperature has been exceeded, the BIOS sends instructions to adjust theprocessor clock speed and fan speed to make a transition to a forcedcooling mode (162). Entry into the forced cooling mode changes the speedof an internal cooling fan and forcibly reduces the clock speed of theCPU and video. However, if the test at step (158) indicates the targettemperature has not been exceeded, the BIOS issues instructions toadjust the fan speed and clock speed of the CPU for immediate transitionto the laptop use mode (160). Entry into the laptop use mode adjusts thespeed of the cooling fan, the speed of the CPU, and video to balanceperformance with thermal output. Following step (162), the BIOS is setto receive an interrupt after a predefined period of time (164). In oneembodiment, the predefined period of time may be about 20 seconds,although this time period may be adjusted to be increased or decreasedas necessary. After the predefined period of time has lapsed, the BIOSreceives an interrupt (166), which results in issuance of instructionsto adjust the fan speed and clock speed of the CPU for immediatetransition to the laptop use mode (168), i.e. change the cooling fanspeed as well as CPU and video performance settings. Accordingly, theprocess illustrating in this embodiment demonstrates a method formaintaining the rapid cooling mode for a defined period of time inresponse to a lift movement of the laptop from a stationary position.

FIG. 5 is a flow chart (200) illustrating a method for maintaining arapid cooling mode for a defined period of time before restoration ofthe laptop use mode. Following the device driver notifying the powermanager utility that the system has entered a laptop use mode (202), thepower manager utility notifies the BIOS of the entry into the laptop usemode (204). The BIOS reads the temperatures of the CPU and video withuse of temperature sensors (206). Thereafter, a test is conducted todetermine whether or not a target internal temperature in the laptop hasbeen exceeded (208). The target internal temperature is a designatedtemperature set as a limit which if exceeded will require the thermalmanagement system to enter into a cooling phase. If the test at step(208) indicates the target temperature has been exceeded, the BIOS sendsinstructions to adjust the processor clock speed and fan speed to make atransition to a forced cooling mode (210). Entry into the forced coolingmode changes the speed of an internal cooling fan and forcibly reducesthe clock speed of the CPU and video. However, if the test at step (208)indicates the target temperature has not been exceeded or the forcedcooling mode has been entered at step (210), the BIOS issuesinstructions to adjust the fan speed and clock speed of the CPU forimmediate transition to the laptop use mode (212). Entry into the laptopuse mode adjusts the speed of the cooling fan, the processor clock, andvideo settings to balance performance with thermal output. Simultaneouswith (212), the BIOS is set to receive an interrupt when the internaloperating temperature becomes equal to or lower than a predesignatedtarget temperature (214). The internal operating temperature isdetermined based upon the received temperature sensor data which isperiodically gathered and processed at predefined time intervals (216).Such time intervals may be adjusted to be lengthened or shortened asdeemed necessary to provide an optimal level of performance. When theinternal operating temperature attains the predesignated targettemperature, the BIOS is notified and issues instructions to adjust thefan speed and clock speed of the CPU for immediate transition to thelaptop use mode (218), i.e. change the cooling fan speed as well as CPUand video performance settings. Accordingly, the process illustrating inthis embodiment demonstrates a method for maintaining the rapid coolingmode for an undefined period of time until a target temperature isattained in response to a lift of the laptop from a stationary position.

There are different methods that may be employed to thermally manageoperation of a computer. Such methods include employing a fan for forcedair cooling, adjusting the processor clock speed, and video performancesettings. In one embodiment, if the forced air cooling is the optimaltool for thermal management, the temperature at which forced air coolingis initiated may be set to accommodate adjustments of the fan speedaccording to the amount of generation of heat when the amount of taskprocessing is fixed. Similarly, in another embodiment, if the adjustmentof the processor speed is the optimal tool for thermal management, thetemperature at which speed adjustment is initiated may be set accordingto the amount of heat generation in conjunction with a determination ofwhen processing speed may be sacrificed. In addition to adjusting fanspeed and the process clock, the video performance settings may also beadjusted. Each of the embodiments may be employed individually or incombination to attain a balance between an acceptable performance leveland a casing surface temperature.

Advantages Over The Prior Art

A higher casing surface temperature limit can be set for use of thelaptop computer on a stationary surface. This provides a reduction innoise level and improved performance associated with a higher processorspeed and video performance settings when the laptop is set in on astationary surface. However, accurate detection of a lift movement ofthe processor in combination with implementation of a rapid cooling modeprevents discomfort associated with placement of the laptop computerfrom the stationary surface to a non-stationary surface, such as the lapof the user. The rapid cooling mode is implemented for a short durationuntil a desired surface casing temperature is attained. During the rapidcooling mode, the noise level may increase and the processor speed andvideo settings may be decreased. However, at such time as the desiredcasing surface temperature is attained, the fan speed, the processorclock, and video performance settings may be adjusted to reduce noiselevel and improved performance in conjunction with maintaining a desiredsurface casing temperature.

Alternative Embodiments

It will be appreciated that, although specific embodiments of theinvention have been described herein for purposes of illustration,various modifications may be made without departing from the spirit andscope of the invention. In particular, thermal management may beemployed with a laptop computer or any other product with electroniccomponents that have a high thermal output. Such products may include apersonal digital assistant, or other categories of electronic handhelddevices. Additionally, the thermal management may be employed inresponse to a lift movement of the computer from a stationary surface toa non-stationary surface, as well as a lift movement from anon-stationary surface to a stationary surface. Accordingly, the scopeof protection of this invention is limited only by the following claimsand their equivalents.

1. A method for cooling a portable computing apparatus comprisingdetecting movement of said computer from a stationary surface, includinga change in inclination of a casing of said computer; determining if atarget temperature is exceeded in response to said movement; andtransitioning said computer to an alternative cooling state in responseto a positive determination.
 2. The method of claim 1, furthercomprising switching to a cooling phase of heat producing hardware insaid computer in response to determining said target temperature hasbeen exceeded.
 3. The method of claim 1, wherein the step oftransitioning said computer to an alternative cooling state includesBIOS sending instructions to adjust processor clock and fan speed. 4.The method of claim 2, wherein said cooling phase allows said targettemperature to be attained in a short time interval.
 5. The method ofclaim 4, further comprising switching to a laptop cooling statefollowing said cooling phase operating for a predefined time interval.6. The method of claim 1, further comprising switching to a laptopcooling state following an internal temperature reaching a targettemperature.
 7. The method of claim 1, wherein said movement is detectedby an accelerometer.
 8. A portable computing apparatus comprising adetector that senses tilt movement of said computer from a surface; asensor that determines if a target temperature is exceeded in responseto said tilt movement; and a controller that transitions said computerto an alternative cooling state in response to a positive determination.9. The apparatus of claim 8, further comprising a manager that switchesheat producing hardware in said computer to a cooling phase in responseto a determination that said target temperature has been exceeded. 10.The apparatus of claim 9, wherein said manager is in communication withBIOS to send instructions to adjust processor clock and fan speed totransition to said cooling phase.
 11. The apparatus of claim 10, whereinsaid processor clock and fan speed adjustment reduces performance of theprocessor and video.
 12. The apparatus of claim 11, further comprising aswitch by said controller to a laptop cooling state after operation ofsaid cooling phase for a predefined time interval.
 13. The apparatus ofclaim 8, further comprising a switch by said controller to a laptopcooling state after an internal temperature has reached a targettemperature.
 14. The apparatus of claim 8, wherein tilt is detected byan accelerometer.
 15. An article comprising: means for detectingmovement of a computer from a stationary surface; means for determiningif a target temperature is exceeded in response to said movement; andmeans for transitioning said computer to an alternative cooling state inresponse to a positive determination.
 16. The article of claim 15,further comprising means for switching to a cooling phase of heatproducing hardware in said computer in response to said targettemperature determination means.
 17. The article of claim 16, whereinsaid means for switching to a cooling phase includes BIOS sendinginstructions to adjust hardware elements with heat byproduct.
 18. Thearticle of claim 17, wherein said hardware elements are selected fromthe group consisting of: processor clock and fan speed.
 19. The articleof claim 17, further comprising means for switching to a cooling statefollowing said cooling phase operating for a predefined time interval.20. The article of claim 15, further comprising means for switching to acooling state following an internal temperature reaching a targettemperature.